TY - JOUR
T1 - Catalytic cyclohexane oxidation to KA oil using novel hydrosoluble copper(I) complexes bearing aminophosphine ligands
T2 - Water as a selectivity promoter
AU - Reis Conceição, Nuno
AU - Mahmoud, Abdallah G.
AU - Guedes da Silva, M. Fátima C.
AU - Mahmudov, Kamran T.
AU - Pombeiro, Armando J.L.
N1 - Publisher Copyright:
© 2023 The Author(s)
PY - 2023/10
Y1 - 2023/10
N2 - Reacting the alkylated 1,3,5-triaza-7-phosphatricyclo[3.3.1.1]decane (PTA), namely (PTA-CH2-C6H4-p-COOH)Br (1) or (PTA-CH2-C6H3-p-OH-m-CHO)Cl (2), with CuBr, CuI or [Cu(CH3CN)4]BF4, under mild conditions using different stoichiometric ratios resulted in the formation of the new water soluble copper complexes [CuBr2(PTA-CH2-C6H4-p-COOH)2]X (X = Br {3a}, I {3b} or BF4 {3c}), [CuBr(PTA-CH2-C6H4-p-COOH)3]Br3 (4) and [CuCl2(PTA-CH2-C6H3-p-OH-m-CHO)2]X (X = I {5a} or Cl {5b}). The compounds were characterized using multinuclear NMR, FTIR, ESI-MS and elemental analysis. The molecular structure of the neutral form of 3 was established by single crystal X-ray diffraction. In a homogeneous aqueous medium, the catalytic activity of the hydrophilic complexes was assessed for the cyclohexane oxidation to the KA oil (a mixture of cyclohexanone and cyclohexanol). The selectivity towards cyclohexanone is controlled by water, increasing with the H2O amount, and becoming higher than that of cyclohexanol for the 25–75% range of water in the solvent composition. Complex 5a exhibited the highest catalytic activity, achieving up to 21% conversion after 4 h at 50 °C using 0.5 mol% of the catalyst. Utilizing a similar loading of 5a, under microwave irradiation, afforded 18% of yield after 1.5 h at 70 °C.
AB - Reacting the alkylated 1,3,5-triaza-7-phosphatricyclo[3.3.1.1]decane (PTA), namely (PTA-CH2-C6H4-p-COOH)Br (1) or (PTA-CH2-C6H3-p-OH-m-CHO)Cl (2), with CuBr, CuI or [Cu(CH3CN)4]BF4, under mild conditions using different stoichiometric ratios resulted in the formation of the new water soluble copper complexes [CuBr2(PTA-CH2-C6H4-p-COOH)2]X (X = Br {3a}, I {3b} or BF4 {3c}), [CuBr(PTA-CH2-C6H4-p-COOH)3]Br3 (4) and [CuCl2(PTA-CH2-C6H3-p-OH-m-CHO)2]X (X = I {5a} or Cl {5b}). The compounds were characterized using multinuclear NMR, FTIR, ESI-MS and elemental analysis. The molecular structure of the neutral form of 3 was established by single crystal X-ray diffraction. In a homogeneous aqueous medium, the catalytic activity of the hydrophilic complexes was assessed for the cyclohexane oxidation to the KA oil (a mixture of cyclohexanone and cyclohexanol). The selectivity towards cyclohexanone is controlled by water, increasing with the H2O amount, and becoming higher than that of cyclohexanol for the 25–75% range of water in the solvent composition. Complex 5a exhibited the highest catalytic activity, achieving up to 21% conversion after 4 h at 50 °C using 0.5 mol% of the catalyst. Utilizing a similar loading of 5a, under microwave irradiation, afforded 18% of yield after 1.5 h at 70 °C.
KW - Copper complexes
KW - Cyclohexane
KW - KA oil
KW - Oxidation
KW - Phosphine ligands
UR - https://www.scopus.com/pages/publications/85169836157
U2 - 10.1016/j.mcat.2023.113512
DO - 10.1016/j.mcat.2023.113512
M3 - Article
AN - SCOPUS:85169836157
SN - 2468-8231
VL - 549
JO - Molecular Catalysis
JF - Molecular Catalysis
M1 - 113512
ER -